Vehicle fault diagnostic system

ABSTRACT

Vehicle data detected in a vehicle  10  is transmitted to an information center  12  so as to detect a fault. When detecting generation of the fault, the information center  12  instructs the vehicle to perform a fault identification process. Identification of the fault location is performed while using mutual communication. When the detected fault is one that requires a recovery countermeasure, the information center  12  instructs the vehicle to perform a recovery process. The recovery process is performed while using mutual data communication so as to eliminate the influence of the fault.

TECHNICAL FIELD

The present invention relates to a vehicle fault diagnostic system, andmore particularly to a vehicle fault diagnostic system including avehicle and an information center that are capable of communicating witheach other.

BACKGROUND ART

A known conventional system disclosed, for instance, by Japanese PatentLaid-Open No. 2002-73153 diagnoses a vehicle condition within thevehicle and, if it is anticipated that a fault may occur, transmitsrelevant information to a servicing institution via a communicationdevice. Before the vehicle becomes unable to run on a road, theconventional system makes it possible to avoid an inconvenience, whichmay arise out of a vehicle fault, by prompting an user to take emergencycountermeasures or to bring the vehicle into a servicing institution.

However, the above conventional system finishes a vehicle faultdiagnosis within a vehicle, and communicates with an externalinstitution only when it transmits fault diagnosis results. As suchbeing the case, the above conventional system needs to store the wholeinformation necessary for fault diagnostic processing within thevehicle.

Further, if a fault occurs to affect the vehicle's run, the aboveconventional system supplies information to an external institution evenif the severity of the fault is low. When the intended purpose is toprevent the vehicle from becoming disabled, the vehicle does not alwayshave to transmit the information to an external if the severity of thefault is low and does not immediately disable the vehicle. In thisrespect, the above conventional system unnecessarily increases the loadon a vehicle's information process.

The present invention has been made in view of the above circumstances.It is an object of the present invention to provide a vehicle faultdiagnostic system that is capable of taking early countermeasuresagainst a vehicle fault and reduces information processing load on thevehicle by establishing communication between the vehicle and anexternal institution.

Japanese Patent Laid-Open No. 2002-202003 discloses a system thatchronologically stores information regarding to learning values whichare outside a specified range, evaluates the stored information, andnotifies the user of a fault that is about to occur. The above documentalso discloses a technology for transmitting relevant data to a vehicledealer to prompt for early response.

Further, Japanese Patent Laid-Open No. 2002-250248 discloses a systemthat exercises recovery control to inhibit the abnormality fromspreading or expanding not only reports the abnormality when anyabnormality is diagnosed.

DISCLOSURE OF INVENTION

The above object is achieved by a vehicle fault diagnostic system, whichincludes a vehicle and an information center that are capable ofcommunicating with each other and has features described as follows. Thesystem includes vehicle data detection means that is installed in thevehicle to detect vehicle data; fault detection means that is installedin the vehicle or in the information center to detect a vehicle fault inaccordance with said vehicle data; identification process instructionmeans that is installed in the information center to find arising of thevehicle fault and to instruct the vehicle to perform a faultidentification process for identifying the cause of the vehicle fault;identification process execution means that is installed in the vehicleto perform the fault identification process that is instructed;identification process result return means that is installed in thevehicle to return the result of said fault identification process to theinformation center; fault location identification means that isinstalled in the information center to identify the fault location inaccordance with the result of said fault identification process, whichis returned from the vehicle; and identified fault countermeasure meansthat is installed in the information center to take countermeasuresagainst the identified fault.

The above object is also achieved by a vehicle fault diagnostic system,which includes a vehicle and an information center that are capable ofcommunicating with each other and has features described as follows. Thesystem includes vehicle data detection means that is installed in thevehicle to detect vehicle data; fault detection means that is installedin the vehicle or in the information center to detect a vehicle fault inaccordance with said vehicle data; recovery process instruction meansthat is installed in the information center to find arising of thevehicle fault and to instruct the vehicle to perform a recovery processfor eliminating the influence of the vehicle fault; recovery processexecution means that is installed in the vehicle to perform the recoveryprocess that is instructed; and process determination means that isinstalled in the vehicle or in the information center to determine inaccordance with the result of said recovery process whether anotherrecovery process should be continued or not.

The above object is further achieved by a vehicle fault diagnosticsystem, which includes a vehicle and an information center that arecapable of communicating with each other and has features described asfollows. The system includes fault characteristic value detection meansthat is installed in the vehicle to detect a fault characteristic valuestemming from arising of a particular fault; fault seriousnessdetermining means for determining the serious degree of detected saidfault in accordance with the magnitude of said fault characteristicvalue; and supply information limiting means for supplying the detectedinformation about said fault to the information center only when saidserious degree exceeds a judgment value.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a conceptual diagram illustrating the configuration of a firstembodiment of the present invention;

FIG. 2 illustrates a fault diagnostic scheme that is carried out in theevent of a Level 2 and Level 3 fault or defect;

FIG. 3 is a flowchart illustrating processing steps that a vehicle,information center, and dealer respectively perform in compliance withthe concept indicated in FIG. 2;

FIG. 4 is a flowchart illustrating a typical fault identificationprocess that is performed at the information center;

FIG. 5 illustrates the relationship between an AFM measured air amountGa and engine speed Ne under a reference load condition;

FIG. 6 illustrates the relationship between an ISC control amount andAFM measured air amount Ga;

FIG. 7 is a typical flowchart illustrating a recovery process that isperformed at the information center;

FIG. 8 illustrates the relationship between the engine speed Ne andvehicle travel distance that are measured under the same load conditionsduring idling;

FIG. 9 is a flowchart illustrating processing steps that the vehicle,information center, and dealer respectively perform in order toimplement the functionality of a third embodiment of the presentinvention;

FIG. 10 illustrates the relationship between the AFM measured air amountGa and vehicle travel distance prevailing when an ISC opening remainsunchanged;

FIG. 11 illustrates the relationship between the vehicle travel distanceand the amount of an ISC opening (or AFM measured air amount Ga) changethat occurs within reference time when the same change instruction valueis given to an ISC valve;

FIG. 12 is a flowchart illustrating processing steps that are performedin a fourth embodiment of the present invention; and

FIG. 13 illustrates the relationship between the vehicle travel distanceand a sign of ISC valve clogging (AFM measured air amount Ga prevailingwhen the ISC opening remains unchanged).

BEST MODE FOR CARRYING OUT THE INVENTION First Embodiment Configurationof First Embodiment

FIG. 1 is a conceptual diagram illustrating the configuration of a firstembodiment of the present invention. As shown in FIG. 1, a systemaccording to the first embodiment includes a vehicle 10, which is usedby a user, an information center 12, and a dealer 14, which doubles as avehicle servicing institution. As described later, these three cancommunicate information to each other via communication devices.

The vehicle 10 includes an ECU (Electronic Control Unit) 16, a display18, and a communication device 20. The ECU 16 is a unit for controllingthe status of the vehicle 10. It can read vehicle data from variouson-vehicle sensors and drive various on-vehicle actuators.

The ECU 16 is connected to the display 18 that is mounted within avehicle compartment. The display 18 not only presents variousinformation to a vehicle driver/passenger, but also serves as aninterface for allowing the vehicle driver/passenger to enterinformation. The ECU 16 is also connected to the communication device20. The ECU 16 can exchange information with devices installed at theinformation center 12 and dealer 14 via the communication device 20.

A computer system 22 and a communication device 24 are installed at theinformation center 12. Similarly, a computer system 26 and acommunication device 28 are installed at the dealer 14 as well. Thesecomputer systems 22, 26 can exchange information with each other andwith the vehicle 10 via the communication devices 24, 28.

Concept of Fault Diagnosis According to First Embodiment

When recognizing failures or defects that exist in the vehicle 10, thesystem according to the present embodiment classifies them into threedifferent levels. Faults or defects whose importance and urgency is thelowest are hereinafter referred to as “Level 1 faults or defects;”faults or defects are referred to as “Level 2 faults or defects” or“Level 3 faults or defects” as importance and urgency thereof becomehigher.

(Level 1 Faults or Defects)

In the present embodiment, vehicle maintenance information is classifiedas Level 1. More specifically, oil deterioration, oil insufficiency, lowtire air pressure, necessity for tire replacement, low air-conditionergas pressure, inadequate battery function, engine coolant shortage,washer shortage, lamp illumination failure, and other similar faults ordefects are classified as Level 1. When a Level 1 failure or defectoccurs, an on-vehicle process is performed, for instance, to illuminatea warning lamp. In this instance, a fault diagnostic process iscompleted within the vehicle.

(Level 2 Faults or Defects)

For example, abnormal shock within the vehicle and inadequate fuelefficiency are classified as Level 2 faults or defects. Abnormal shockcan be detected, for instance, by an on-vehicle acceleration sensor.Inadequate fuel efficiency can be detected by comparing the fuelconsumption amount prevailing under fixed reference conditions (e.g.,during idling or 40 km/h constant speed running) against a referencevalue.

The above faults do not bring the vehicle to an immediate stop. However,it is conceivable that the above faults may be caused by anyabnormality, and are likely to bring discomfort to the passengers in thevehicle, unlike Level 1 faults or the like. Therefore, when a Level 2failure or defect is detected, the system according to the presentembodiment attempts to identify the cause of the detected faults ordefects and supplies the resulting identification information to thedealer 14, thereby making it possible to take early countermeasuresagainst the detected fault or defect. When identifying the faults, thesystem according to the present embodiment causes the information center12 to perform a part of an identification process for the purpose ofreducing the load on the ECU 10 while allowing the ECU 10 andinformation center 12 to exchange information.

(Level 3 Faults or Defects)

In the present embodiment, faults or defects directly bringing thevehicle to a stop are classified as Level 3. More specifically, anabnormal engine speed Ne decrease, acceleration failure, abnormal sound,abnormal knock, pre-ignition, and other ones that are the signs of anengine stall are classified as Level 3. The abnormal engine speed Nedecrease can be detected in accordance, for instance, with a revolutionspeed sensor output generated during idling. The acceleration failurecan be detected by checking whether proper acceleration is achieved whenthe throttle opening or intake air amount increases.

An abnormal sound can be detected in accordance, for instance, with theoutput of a microphone installed within an engine room. Morespecifically, the place where an abnormal sound is generated, that is,the source of the abnormal sound, can be located by subjecting themicrophone output to frequency analysis and pattern recognition. When anabnormal sound having a high sound pressure is generated in an internalcombustion engine main body or other component important for a vehiclerun, the present embodiment recognizes the abnormal sound as a Level 3failure or defect.

An abnormal knock can be detected by a vibration sensor or cylinderpressure sensor. Pre-ignition can be detected by a cylinder pressuresensor or by making an ion current comparison between combustion starttiming and ignition plug discharge timing.

The above abnormalities can be detected as a sign that the vehicle isabout to become unable to run. When a Level 3 faults or defect isdetected in the vehicle, it is preferred that the cause of the fault ordefect be identified immediately to perform proper maintenance. When itis required to transport the vehicle 10 to the dealer 14, it ispreferred that the vehicle 10 be able to run wherever possible.Therefore, when a Level 3 failure or defect is detected, the systemaccording to the present embodiment attempts to identify the cause ofthe fault or defect, supplies the resulting identification informationto the dealer 14, and performs a recovery procedure within the vehicle10 for deleting the effect of the fault or defect. When identifying thefaults or defect and performing the recovery procedure, the systemaccording to the present embodiment causes the information center 12 toperform a part of a necessary process for the purpose of reducing theload on the ECU 10 while allowing the ECU 10 and information center 12to exchange information.

(Roles of Vehicle 10, Information Center 12, and Dealer 14)

FIG. 2 outlines a fault diagnostic scheme that is carried out in theevent of a Level 2 or Level 3 faults or defect. The fault diagnosticprocess for a Level 1 fault or defect will not be described in detailbelow because it is completed in the vehicle 10 without involvingparticular functions of the information center 12 and dealer 14.

In the vehicle 10, various vehicle data, which are closely related toLevel 2 and Level 3 faults or defects, are detected. For example, thefuel injection time and fuel injection rate for calculating the fuelconsumption amount (fundamental data for a Level 2 fuel efficiencyproblem), the engine speed for judging an engine stall (Level 3), andthe cylinder pressure sensor output for judging an abnormal knock (Level3) and pre-ignition (Level 3) are detected with predetermined samplingtiming. These vehicle data are transmitted from the vehicle 10 to theinformation center 12 as shown in FIG. 2.

The information center 12 receives the vehicle data from the vehicle 10,and analyzes the vehicle data to check for a serious abnormality, thatis, a Level 2 or Level 3 fault or defect. For example, the informationcenter 12 judges whether the fuel consumption amount is significantlyincreased with the passage of time, whether the engine speed Ne isabnormally decreased, and whether cylinder pressure change according toan abnormal knock or pre-ignition is detected by the cylinder pressuresensor.

If no serious abnormality is recognized at the information center 12,the vehicle 10 repeatedly transmits vehicle data to the informationcenter 12. If, on the other hand, a serious abnormality is recognized atthe information center 12, the information center 12 instructs thevehicle 10 to identify the cause of the abnormality, that is, a fault.If, for instance, the engine speed Ne is abnormally decreased, thevehicle 10 is requested to perform a predefined specific process for thepurpose of determining whether the abnormality is caused by a frictionincrease in the internal combustion engine or in some auxiliary devices.

The vehicle 10 performs a designated specific process and then transmitsvehicle data as diagnostics data, which is generated as a result of theprocess, to the information center 12. In a mode for diagnosing theincrease in the internal combustion engine friction, for instance, acombination of intake air amount Ga and engine speed Ne is transmittedto the information center. In a mode for diagnosing the increase in thefriction of each auxiliary device, a combination of the air intakeamounts Ga and engine speeds Ne prevailing before the auxiliary deviceoperation as well as the same prevailing after the auxiliary deviceoperation are transmitted to the information center 12.

In accordance with the vehicle data supplied from the vehicle 10, theinformation center 12 judges whether the fault, that is, the cause ofthe abnormality is identified. If the judgment result indicates that thefault is still not identified, the information center 12 issuesinstructions for making continued efforts to identify the fault. If, onthe other hand, the judgment result indicates that the fault isidentified, the information about the identified fault is supplied tothe dealer 14. Upon receipt of the information, the dealer 14 takesearly countermeasures against the fault. More specifically, the dealer14 starts various actions such as contacting the user and procuringparts necessary for repairs of the vehicle 10.

When the fault is identified, the information center 12 judges whetherthe identified fault is a Level 3 fault or defect, which requires theexecution of a recovery procedure. When the obtained judgment resultindicates that the identified fault is a Level 3 fault or defect, theinformation center 12 instructs the vehicle 10 to perform a recoveryprocedure. More specifically, if the identified fault is an increase inthe internal combustion engine friction, the information center 12instructs the vehicle 10 to increase the amount of idling air. If, onthe other hand, the identified fault is an increase in the friction ofan auxiliary device, the information center 12 instructs the vehicle 10to increase the amount of correction air for the operation of theauxiliary device. Further, if the identified fault is pre-ignition orother defect that cannot readily be recovered from within the vehicle10, the user is instructed to immediately bring the vehicle 10 to thedealer for recovery purposes.

Details of Processing Steps According to First Embodiment

(Overall Process)

FIG. 3 is a flowchart illustrating processing steps that the vehicle 10,information center 12, and dealer 14 respectively perform in accordancewith the above concept. As indicated in the flowchart, the ECU 16 in thevehicle 10 detects a large number of vehicle data concerning the statusof the vehicle 10 (step 100). The vehicle data concerning Level 2 andLevel 3 faults or defects are transmitted to the information center 12(step 102).

In step 110, the information center 12 receives the data from thevehicle 10. The information center 12 then stores the received data in adatabase within the computer system 22 (step 112). More specifically,step 112 is performed to store not only the transmitted vehicle data butalso the ID of the vehicle 10 that has transmitted the data. Next, afault diagnosis is performed in the vehicle 10 in accordance with thereceived latest vehicle data and past vehicle data previously stored inthe database (step 114). More specifically, the faults or defectsclassified to Level 2 and Level 3 are judged one by one whether arisingor not.

After the above diagnostic check, judgment is made for checking whethera serious faults or defect, which belongs to Level 2 or 3 is found outor not (step 116). If no serious faults or defect is recognized, thecomputer system 22 at the information center 12 returns to a state inwhich vehicle data is awaited. If, on the other hand, a serious fault ordefect is recognized, the information center 12 begins to perform afault identification process (step 118).

When the fault identification process starts, the information center 12first instructs the vehicle 10 to initiate an identification process.Next, the information center 12 selects the identification process to beperformed. The information center 12 stores the relationship betweendetected faults or defects and identification processing steps foridentifying the causes of detected faults or defects. The identificationprocess to be performed is selected in accordance with the storedrelationship. When a particular identification process is selected inthis manner, the information center 12 informs the vehicle 10 of thefirst process to be performed for identification purposes and thevehicle data (hereinafter referred to as the “required diagnostic data”)to be confirmed after completion of the first process.

The vehicle 10 receives an identification instruction from theinformation center 12 (step 120), and then begins to perform a processfor acquiring the required diagnostic data (step 122). Morespecifically, the vehicle 10 performs a process that is designated bythe information center 12, and acquires the resulting specific vehicledata as the required diagnostic data. In step 124, the vehicle 10transmits the acquired required diagnostic data to the informationcenter 12. Subsequently, the vehicle 10 repeatedly performs processingsteps 122 until receiving an identification completion instruction (step126).

If the vehicle 10 sends the required diagnostic data to the informationcenter 12 while the fault identification process is being performed, theinformation center 12 notes the required diagnostic data to judgewhether the fault is identified. If it is judged that any furtherprocess needs to be performed for fault identification, the informationcenter 12 informs the vehicle 10 of the next process to be performed andthe associated required diagnostic data. Upon receipt of suchinstructions from the information center 12, the vehicle 10 performsprocessing steps 122 and 124 to send the required diagnostic data to theinformation center 12.

When the information center 12 notes the received required diagnosticdata to conclude that fault identification is completed, the informationcenter 12 notifies the vehicle 10 of the completion of faultidentification. Upon receipt of such a notification, the vehicle 10judges that the condition of step 126 is established. As a result, thefault identification process terminates at both the information center12 and vehicle 10. Further details of the fault identification processwill be given later with reference to FIGS. 4 to 6.

When identifying the fault in the vehicle 10 (step 130), the informationcenter 12 first transmits the information about the identified fault tothe dealer 14 (step 132). Next, the information center 12 judge whetherthe identified fault is a Level 3 fault or defect, which requires theexecution of a recovery procedure (step 134). When the obtained judgmentresult indicates that the execution of a recovery procedure is required,a recovery process is started immediately (step 136).

The dealer 14 waits until the information center 12 transmits identifiedfault data (step 140). Upon receipt of the identified fault data, thedealer 14 stores the ID of the vehicle 10 and the identified fault datain a database within the computer system 26 (step 142).

Next, judgment is made for checking whether the identified faultrequires the execution of early countermeasures (step 144). If thejudgment result indicates that the execution of early countermeasures isrequired, the dealer 14 contacts the user (via e-mail, etc.) andautomatically places an advance order for replacement parts (step 146).

When the above recovery process (step 136) is initiated at theinformation center 12, the information center 12 first instructs thevehicle 10 to start performing a recovery process. Next, the informationcenter 12 selects a particular recovery process that is to be performed.The information center 12 stores the relationship between the identifiedfault and the recovery process for eliminating the influence of thefault. The recovery process to be performed is selected in accordancewith the stored relationship. When a particular recovery process isselected in this manner, the information center 12 notifies the vehicle10 of the process to be executed for recovery purposes and the vehicledata (hereinafter referred to as the “recovery confirmation data”) to beconfirmed after completion of the recovery process.

When the information center 12 issues the above recovery instruction(step 150), the vehicle 10 performs a recovery procedure in compliancewith the recovery instruction (step 152). Specific vehicle datagenerated after the execution of the recovery procedure is then acquiredas the recovery confirmation data. The recovery confirmation dataacquired in this manner is transmitted from the vehicle 10 to theinformation center 12 (step 154). Subsequently, the vehicle 10repeatedly performs processing steps 152 until receiving a recoveryconfirmation instruction (step 156).

When the recovery confirmation data is transmitted from the vehicle 10during recovery process execution, the information center 12 analyzesthe data to judge whether the influence of the fault is eliminated. Ifthe judgment result indicates that the influence of the fault is noteliminated, the information center 12 instructs the vehicle 10 tocontinuously perform a recovery procedure. Upon receipt of such aninstruction, the vehicle 10 performs processing steps 152 and 154 totransmit the recovery confirmation data to the information center 12.

When the information center 12 notes the recovery confirmation data torecognize that the influence of the fault is eliminated, the informationcenter 12 informs the vehicle 10 that recovery is confirmed. Uponreceipt of such a notification, the vehicle 10 judges that the conditionof step 156 is established. As a result, the recovery process terminatesat both the information center 12 and vehicle 10. Further details of therecovery process will be given later with reference to FIG. 7.

(Typical Fault Identification Process)

FIG. 4 is a flowchart illustrating a typical fault identificationprocess that is performed at the information center 12. The faultidentification process shown in FIG. 4 relates to an abnormal decreasein the engine speed Ne. In the present embodiment, the internalcombustion engine is set so that the engine speed Ne does not normallydecrease below 400 rpm. Therefore, when an engine speed Ne of lower than400 rpm is detected, the present embodiment concludes that the enginespeed Ne is abnormally low. In this instance, the information center 12performs a fault identification process by following the steps shown inFIG. 4 for the purpose of identifying the cause of the abnormality.

In the flowchart, although the abnormally low engine speed Ne is handledas a defect that directly leads to an engine stall, the defects directlylead to an engine stall is not limited to this. When, for instance, thecylinder pressure detected by the cylinder pressure sensor is unduly lowor the internal combustion engine output torque detected by a torquesensor is unduly small, the present embodiment may recognize a defectthat directly leads to an engine stall.

In the fault identification process shown in FIG. 4, an identificationprocess for determining whether the engine load is abnormal is initiatedat first (step 160). More specifically, the information center 12requests the vehicle 10 to measure the intake air amount Ga (airflowmeter; AFM measured air amount) and engine speed Ne under a referenceload condition (while an air conditioner, an alternator, a powersteering, and other auxiliary devises imposing a load (hereinafterreferred to as the “auxiliary devices”) are operating), and return themeasured data (required diagnostic data).

FIG. 5 illustrates the relationship between the AFM measured air amountGa and engine speed Ne under the reference load condition. While theload is constant, the engine speed Ne virtually depends on the AFMmeasured air amount Ga. Therefore, the normal relationship between theAFM measured air amount Ga and engine speed Ne can be predefined asindicated in FIG. 5. If the Ne transmitted as the required diagnosticdata is unduly small in relation to the Ga simultaneously transmitted,the information center 12 concludes that the internal combustion engineload is abnormal. In such an instance, a load abnormality detectionroutine is also started for the purpose of identifying the fault (step162).

In the load abnormality detection routine, the information center 12sequentially requests the vehicle 10 to forcibly drive or stop theauxiliary devices, one by one, while maintaining the air amount Gaconstant, and return the engine speed change arising between after andbefore the start or stop of each auxiliary device to the informationcenter 12 as the required diagnostic data. When the auxiliary devicesindividually start or stop, the internal combustion engine load changes,thereby changing the engine speed Ne. The information center 12 storesan engine speed change amount for each auxiliary device, and comparesthe engine speed change amount, which is transmitted as the requireddiagnostic data, against the stored value to judge whether the load oneach auxiliary device is appropriate.

If an unduly great engine speed change amount is found in any auxiliarydevice, the information center 12 concludes that the auxiliary device isfaulty. If, on the other hand, no fault is found in any auxiliarydevice, the information center 12 concludes that there is an unduefriction increase in the internal combustion engine main body or aproblem with a drive train. When the fault is located in this manner,the information center 12 issues an identification completioninstruction to the vehicle 10 as described earlier so that the faultidentification process ends. In addition, the information center 12supplies the information about the identified fault to the user (vehicle10) and dealer 14.

If the internal combustion engine load is not found to be abnormal whenan identification process is performed in step 160, the informationcenter 12 starts an identification process for checking whether an idlespeed control valve (ISC valve) is clogged (step 164). Morespecifically, the information center 12 requests the vehicle 10 tomeasure an ISC control amount (valve opening degree or drive duty cycle)and AFM measured air amount Ga, and return the measured data (requireddiagnostic data) to the information center 12.

FIG. 6 illustrates the relationship between the ISC control amount andAFM measured air amount Ga. Originally, the ISC control amount isvirtually proportional to the AFM measured air amount Ga, their normalrelationship, therefore, can be predefined as indicated in FIG. 6. Ifthe AFM measured air amount Ga, which is returned as the requireddiagnostic data, is unduly small in relation to the ISC control amount,which is returned simultaneously, the information center 12 concludesthat the ISC valve is clogged (step 166). When the fault is identifiedin this manner, the information center 12 issues an identificationcompletion instruction to the vehicle 10 so that the faultidentification process ends. In addition, the information center 12notifies the user (vehicle 10) and dealer 14 of the ISC valveabnormality and the necessity for cleaning or replacing the ISC valve.

If the ISC valve is not found to be clogged when an identificationprocess is performed in step 164, the information center 12 starts anidentification process to check for an open circuit or short circuit inthe ISC valve (step 168). More specifically, the information center 12requests the vehicle 10 to measure an ISC valve terminal voltage andreturn the measured value to the information center 12 as the requireddiagnostic data.

If there is an open circuit or short circuit in a drive circuit for theISC valve, the ISC valve terminal voltage is abnormal. If the terminalvoltage returned as the required diagnostic data significantly differsfrom a predefined normal value, the information center 12 concludes thatthere is an open circuit or short circuit in the ISC valve (step 170).When the fault is identified in this manner, the information center 12issues an identification completion instruction to the vehicle 10 sothat the fault identification process ends. In addition, the informationcenter 12 notifies the user (vehicle 10) and dealer 14 of anopen-circuited or short-circuited ISC valve and the necessity forrunning a wiring check or replacing the ISC valve.

The above example assumes that the terminal voltage is measured to checkthe ISC valve for an open circuit/short circuit. However, the presentinvention is not limited to such an open circuit/short circuit diagnosismethod. Alternatively, an open-circuit check may be conducted byforcibly operating the ISC valve to check whether the relationshipbetween the resulting ISC control amount and AFM measured air amount Gais proper. Another alternative judgment method is to check whether anISC valve terminal current is normal.

If the ISC valve is not found to be open-circuited or short-circuitedwhen an identification process is performed in step 168, the informationcenter 12 starts an identification process to check whether the ISCvalve is stuck (step 172). More specifically, the information center 12requests the vehicle 10 to return the ISC valve operation amount(opening degree instruction) and actual opening degree (opening sensoroutput) to the information center 12 as the required diagnostic data.

If the ISC valve is stuck, it does not open to in accordance with theoperation amount. If a proper relationship does not exist between theopening degree and the operation amount, which is returned as therequired diagnostic data, the information center 12 concludes that theISC valve is stuck (step 174). When the fault is identified in thismanner, the information center 12 issues an identification completioninstruction to the vehicle 10 so that the fault identification processends. In addition, the information center 12 notifies the user (vehicle10) and dealer 14 of a stuck ISC valve and the necessity for cleaning orreplacing the ISC valve.

The above example assumes that the ISC valve is provided with an openingdegree sensor. However, if the ISC valve is not provided with an openingdegree sensor, the AFM measured air amount Ga may be used as asubstitute for the opening degree and as the basis for judging whetherthe ISC valve is stuck. The above example also assumes that a stuck ISCvalve is checked for by determining whether there is a proper staticrelationship between the ISC valve control amount and the opening degree(or AFM measured air amount Ga). However, the present invention is notlimited to the use of such a judgment method. Alternatively, a stuck ISCvalve may be checked for by forcibly operating the ISC valve todetermine whether there is a proper relationship between the resultingcontrol amount change and the change in the opening degree or AFMmeasurement air amount Ga.

If the ISC valve is not found to be stuck when an identification processis performed in step 172, the information center 12 concludes that theISC valve is normal. In this instance, the information center 12concludes that the entire intake system for the internal combustionengine is clogged (step 176). Further, the information center 12notifies the user (vehicle 10) and dealer 14 of a clog in the entireintake system and the necessity for cleaning or replacing an aircleaner.

As described above, when a Level 2 or Level 3 failure or defect isdetected, the system according to the present embodiment can identify afault, which is the cause of the fault or defect, while allowing theinformation center 12 and vehicle 10 to exchange information. In thisinstance, a major information process for fault identification isperformed in the information center 12. Therefore, the load on the ECU16 in the vehicle 10 is sufficiently reduced. As a result, the systemaccording to the present embodiment provides a function for identifyinga serious fault without requiring the on-vehicle ECU 16 to have a highprocessing capacity and allowing the dealer 14 or other externalinstitution to share the information about the fault.

(Typical Recovery Process)

When an identified fault is a Level 3 fault, the information center 12performs a recovery process to eliminate the influence of the fault asdescribed earlier. FIG. 7 is a typical flowchart illustrating therecovery process to be performed at the information center 12. Therecovery process shown in FIG. 7 is performed when the engine speed Neis found to be abnormally low. More specifically, FIG. 7 shows arecovery process that is performed when it is found that the enginespeed Ne is unduly lowered by an abnormal increase in theair-conditioner load.

In the recovery process shown in FIG. 7, an instruction for increasingthe correction-increasing amount in the intake air amount Ga forair-conditioner operation by a predetermined amount is first issued tothe vehicle (step 180). To prevent the engine speed Ne from beingdecreased by an air-conditioner operation, the vehicle 10 adds anair-conditioner correction amount to a basic intake air amount Ga duringan air-conditioner operation. Upon receipt of the instruction issued instep 180, the vehicle 10 performs a process for increasing theair-conditioner correction amount. As a result, the present embodimentinhibits the engine speed Ne from decreasing during an air-conditioneroperation no matter whether the air-conditioner load increases.

Next, the information center 12 judges whether an idling intake airamount exceeds an ISC guard value due to the above-mentioned increase inthe air-conditioner correction amount (step 182). In the vehicle 10, anISC guard is set for the idling intake air amount in order to prevent anunnecessary high output from being generated during idling. Therefore,when an instructed intake air amount Ga exceeds the ISC guard because ofthe increase in the air-conditioner correction amount, the request foran increase in the air-conditioner correction amount may not always bethoroughly fulfilled, since the actual intake air amount Ga isrestricted by the guard.

Accordingly, the information center 12 instructs the vehicle 10 toincrease the ISC guard value as needed to prevent it from being exceededby the idling intake air amount Ga, when it is judged that the idlingintake air amount Ga is about to exceed the ISC guard value (step 184).In the vehicle 10, therefore, the requested increase amount for theair-conditioner correction amount can be actually reflected in theidling intake air amount Ga without regard to the existence of the ISCguard.

When instructing the vehicle 10 to increase the air-conditionercorrection amount, the information center 12 also requests the vehicle10 to return as appropriate the idling speed Ne measured after theair-conditioner correction amount increase. Upon receipt of the idlingspeed Ne, the information center 12 notes the received idling speed Neand judges whether the engine speed Ne is restored to a normal value,that is, 400 rpm or higher (step 186).

If the obtained judgment result indicates that the engine speed Ne isnot restored to the normal value, processing step 180 and followingsteps are repeated to increase the air-conditioner correction amountagain. If, on the other hand, the judgment result indicates that theengine speed Ne is restored to the normal value, step 188 is performedto judge whether the normal engine speed value has been maintained for apredetermined period of time.

If the obtained judgment result indicates that the normal engine speedvalue has not been maintained for the predetermined period of time,processing step 186 is repeated. If the judgment result obtained aftersuch processing step repetition indicates that the normal engine speedvalue has been maintained for the predetermined period of time, theinformation center 12 verifies that the engine speed Ne is restored tonormal, and informs the vehicle 10 of such engine speed normalization(step 190). As a result, the vehicle 10 recognizes that the restorationprocess is terminated (refer to step 156).

The engine speed Ne unduly lowers not only when the air-conditioner loadis unduly increased, but also when the load on another auxiliary deviceis increased, when the internal combustion engine main body friction isincreased, and when the ISC valve is clogged, open-circuited,short-circuited, or stuck. In a case where the load on an auxiliarydevice other than the air conditioner is increased, the engine speed Necan be restored to normal by increasing the correction air amount as isthe case when the load on the air conditioner is increased. In a casewhere the internal combustion engine main body friction is increased,the engine speed Ne can be restored to normal by increasing the basicintake air amount. Further, in a case where the ISC valve is clogged,open-circuited, short-circuited, or stuck, the influence of the faultcan be eliminated by adjusting the required air amount with other airamount control device which is used with the ISC valve, such as anelectronic throttle, or power steering air amount control valve. Itmeans that the system according to the present embodiment can recoverthe proper engine speed Ne by performing an appropriate recovery processto take the above-mentioned countermeasures in accordance with theidentified fault when an undue decrease in the engine speed Ne isdetected.

Level 3 faults or defects for which the present embodiment performs arecovery process include not only an undue decrease in the engine speedNe, which is mentioned above, but also an acceleration failure, abnormalsound, abnormal knock, and pre-ignition. As regards the accelerationfailure, its influence can be eliminated by increasing the air amount toa possible extent as far as it is caused by intake air amountinsufficiency. The influence of the abnormal knock can be eliminated bycorrecting the ignition timing. The system according to the presentembodiment performs procedures for eliminating the influence of a faultas a recovery process when the influence of the fault can be eliminatedby correcting the control amount within the vehicle 10 as describedabove. If the influence of a fault (e.g., pre-ignition) cannot beeliminated by performing a recovery process within the vehicle 10, thesystem according to the present embodiment performs procedures forinforming the user of the necessity for immediate servicing at aservicing institution as a recovery process.

As described above, the system according to the present embodimentenables the vehicle 10 to identify a fault, which is the cause of aserious failure or defect (Level 2 or Level 3 fault or defect)encountered in the vehicle 10. Further, if the identified fault is anurgent fault (Level 3 fault), the system according to the presentembodiment immediately performs a recovery process on the vehicle 10 toeliminate the influence of the fault. Consequently, the system accordingto the present embodiment effectively prevents the vehicle 10 frombecoming unable to run on a road.

The system according to the present embodiment permits the informationcenter 12 to perform a major process for identifying a fault(identification process) and a major process for eliminating theinfluence of an identified fault (recovery process). As a result, thesystem according to the present embodiment provides excellent advantagesdescribed above without imposing a heavy load on the on-vehicle ECU 16.

In the first embodiment, which has been described above, the informationcenter 12 performs a fault diagnostic process (step 114) for detecting aLevel 2 or Level 3 fault or defect in accordance with vehicle data.However, the present invention is not limited to such a fault diagnosticprocess execution. Alternatively, the vehicle 10 may perform a faultdiagnostic process and transmit only the information about a detectedfault or defect to the information center 12.

The first embodiment, which has been described above, causes theinformation center 12 to inform the vehicle 10 of the identificationprocessing steps to be sequentially performed for the purpose ofidentifying the cause of a detected fault or defect, and causes thevehicle 10 to transmit sequentially obtained required diagnostic data tothe information center 12. However, the present invention is not limitedto the use of such a method. An alternative is to let the informationcenter 12 inform the vehicle 10 of only a starting point of a series ofprocessing steps that are to be performed for identifying the cause of adetected fault or defect, allow the vehicle 10 to perform the subsequentprocessing steps until fault identification is completed, and cause thevehicle 10 to transmit only the information about an identified fault tothe information center 12.

When performing a recovery process to eliminate the influence of anidentified fault, the first embodiment, which has been described above,causes the information center 12 to inform the vehicle 10 of theprocessing steps to be sequentially performed, and causes the vehicle 10to sequentially transmit the resulting post-processing data to theinformation center 12. However, the present invention is not limited tothe use of such a method. An alternative is to let the informationcenter 12 inform the vehicle 10 of only the first recovery process stepto be performed on an identified fault, and allow the vehicle 10 toperform the subsequent processing steps until recovery is completed.

Second Embodiment

A second embodiment of the present invention will now be described withreference to FIG. 3 again. The second embodiment of the presentinvention can be implemented by using the same hardware configuration asfor the first embodiment. The system according to the first embodiment,which has been described earlier, unconditionally handles an abnormalengine speed decrease, acceleration failure, abnormal sound, abnormalknock, and pre-ignition, which are the signs of an engine stall, as aLevel 3 fault or defect.

However, when the engine speed Ne is abnormally decreased, for instance,to a level slightly below 400 rpm, it is not highly likely that theengine would stall immediately. In other words, when the engine speed Neis abnormally decreased to approximately 400 rpm, it is not alwaysnecessary to take immediate countermeasures. If a fault identificationor recovery process is performed immediately in such a situation, theload on the ECU 16 or computer system 22 may unnecessarily increase.

The same also holds true for an acceleration failure, abnormal sound,and abnormal knock. These faults or defects do not always have to berecognized as a Level 3 fault or defect. On the contrary, these faultsor defects should be judged to classify the severity, thus, only severefaults or defects should be classified to Level 2 or Level 3 faults ordefects in order to prevent the load on the ECU 16 and computer system22 from being unduly increased. Further, only the severest faults ordefects should be classified as Level 3 faults or defects to limit thetarget for fault identification control and the target for recoverycontrol.

As such being the case, the system according to the present embodimentclassifies an undue decrease in the engine speed Ne into three differentlevels, handling it as Level 3 only when Ne<200 rpm, as Level 1 when 200rpm ≦Ne<300 rpm, and as Level 1 when 300 rpm≦Ne<400 rpm. The presentembodiment also classifies an acceleration failure, abnormal sound, andabnormal knock into three different levels. More specifically, thepresent embodiment handles the severest faults as Level 3 faults,moderate faults as Level 2 faults, and the least severe faults as Level1 faults.

Under the above circumstances, acceleration failures are classified intothree different levels depending on the detected acceleration or themagnitude of a vehicle speed change. Abnormal sounds are classified intothree different levels depending on the part identified as an abnormalsound source and on the sound pressure level. An abnormal knock isclassified into three different levels depending on the knock intensitydetected by a knock sensor or the like. However, pre-ignition shouldalways be recognized as an urgent fault without regard to its intensity.Therefore, the present embodiment always recognizes pre-ignition as aLevel 3 failure or defect.

To implement the functionality described above, the system according tothe present embodiment causes the ECU 16 in the vehicle 10 to transmitonly vehicle data classified in accordance with the above-mentioneddefinition as Level 2 or Level 3 to the information center 14 in step102, which is shown in FIG. 3. Meanwhile, the computer system 22 at theinformation center 12 performs step 116, which is shown in FIG. 3, torecognize only faults or defects belonging to Level 2 or Level 3 inaccordance with the above-mentioned definition as serious faults. Instep 134, the computer system 22 at the information center 12 complieswith the above definition and recognizes only Level 3 faults as faultsfor which a recovery procedure needs to be performed.

Therefore, even when an undue decrease in the engine speed Ne or anabnormal knock is recognized, the system according to the presentembodiment will omit the information exchange between the vehicle 10 andthe information center 12 if it is classified to a Level 1 fault. Ifsuch a fault is recognized as a Level 2 fault, the system according tothe present embodiment performs a fault identification process butrefrains from performing a recovery process. As a result, thecomputation load imposed on the ECU 16 and computer system 22 by thesystem according to the present embodiment is lighter than that isimposed by the system according to the first embodiment.

Third Embodiment

A third embodiment of the present invention will now be described withreference to FIGS. 8 to 11. The system according to the third embodimentis implemented when the ECU 16 and computer units 22, 26, which areincluded in the hardware configuration according to the firstembodiment, perform processing steps that are described later withreference to FIG. 9 instead of the processing steps indicated in FIG. 3.

Some of vehicle data 10 that is detected in the vehicle 10 are affectedby changes due to time passage arising in the internal combustion engineand other. For example, the engine speed Ne prevailing under fixed loadconditions correlates with an increase/decrease in the internalcombustion engine friction. FIG. 8 illustrates the relationship betweenthe engine speed Ne and vehicle travel distance that are measured underthe same load conditions during idling.

In general, the internal combustion engine friction decreases with anincrease in the degree of engine running-in. In a small travel distanceregion, therefore, the engine speed Ne shown in FIG. 8 tends to increasein proportion to the travel distance. When various parts considerablywear due to an increased travel distance, the engine speed Ne begins todecrease with an increase in running resistance.

As for the idling engine speed Ne, there is a lower-limit value which isnecessary for assuring that the internal combustion engine keeps onrunning steadily. The NG level shown in FIG. 8 represents thelower-limit value. When the lower-limit value for the engine speed Ne ispredetermined and the tendency of an engine speed decrease in relationto the travel distance is grasped, it is possible to estimate the traveldistance remaining before the actual Ne value reaches the NG level. Thepresent embodiment causes the information center 12 to estimate theremaining travel distance, and uses the result of estimation as themaintenance information for the vehicle 10.

FIG. 9 is a flowchart illustrating processing steps that the vehicle 10,information center 12, and dealer 14 respectively perform in order toimplement the above functionality. As indicated in the figure, the ECU16 in the vehicle 10 judges whether a reference idle state isestablished (step 200). The reference idle state is defined as a statein which the internal combustion engine idles under a virtually fixedload. More specifically, it is preferred that the alternator generates aconstant load while the other auxiliary devices are stopped. When it isjudged that the reference idle state is established, the vehicle 10transmits the currently detected engine speed Ne to the informationcenter 12 (step 202).

The information center 12 receives the engine speed data from thevehicle 10 (step 210), and then stores the data in a database within thecomputer system 22 (step 212). More specifically, the database storesthe transmitted engine speed Ne and the ID of the vehicle 10 that hastransmitted the data. Next, the current tendency toward an engine speedchange is computed in accordance with the latest engine speed Ne andprevious engine speed Ne stored in the database (step 214).

Then, judgment is made to determine whether the computation resultindicates decrease tendency of the engine speed Ne (step 216). If theobtained judgment result does not indicate the decrease tendency of theengine speed Ne, it is concluded that the engine speed Ne will notpossibly decrease to the NG level. Therefore, the current processterminates. If, on the other hand, the obtained judgment resultindicates that the engine speed Ne tends to decrease, the traveldistance remaining before the engine speed Ne reaches the NG level iscalculated in accordance with the gradient of the engine speed Nerelative to the travel distance and a predefined NG value (e.g., 400rpm) for the engine speed (step 218). The calculated travel distance isthen transmitted to the vehicle 10 and dealer 14 (step 220).

The vehicle 10 receives the above NG information (travel distance) (step230), which is transmitted from the information center 12, and thenperforms a process for presenting the information to thedriver/passenger in the vehicle 10, that is, the user (step 232).

Meanwhile, the dealer 14 receives the NG information (step 240), andthen stores the ID of the vehicle 10 and the received data, that is, thetravel distance remaining before the NG state is established, in thedatabase within the computer system 26 (step 242). Next, the dealer 14performs a process to take early countermeasures automatically for thepurpose, for instance, of sending a message to the user (via e-mail orthe like) and placing an advance order for replacement parts (step 244).

As described above, the system according to the present embodiment canestimate in advance the travel distance remaining before the vehicle 10becomes unable to run by monitoring for engine speed changes during thereference idle state. Further, the system according to the presentembodiment can let the information center 12 perform a major processthat is necessary for such estimation. As a result, the system accordingto the present embodiment implements a function for predicting a seriousfault of the vehicle 10 and taking early measures against the faultwithout imposing a great load on the ECU 16.

The third embodiment, which has been described above, predicts thetravel distance remaining before the NG state is invoked by an increasein the internal combustion engine friction. However, the target forprediction is not limited to such a travel distance. An alternativetarget for prediction may be a travel distance that is remaining beforethe NG state is established due to a fault in the ISC valve or anincrease in an auxiliary device friction. Hereinafter, a method forpredicting the travel distance remaining before the NG state isestablished due to a fault in the ISC valve will now be described as theexplanation of a typical modified version of the third embodiment.

FIG. 10 illustrates the relationship between the AFM measured air amountGa and vehicle travel distance prevailing when an ISC opening degreeremains unchanged. As indicated in FIG. 10, the AFM measured air amounttends to decrease at the same ISC opening degree after the ISC valvebegins to become clogged. Therefore, when the tendency to decrease ismonitored, it is possible to predict the travel distance remainingbefore the engine stalls due to a clogged ISC valve.

FIG. 11 illustrates the relationship between the vehicle travel distanceand the amount of an ISC opening degree (or AFM measured air amount Ga)change that occurs within reference time when the same changeinstruction value is given to the ISC valve. While the ISC valve'sresponse is normal, there arises normal amount of change in the ISCopening degree and AFM measured air amount Ga within the above referencetime. However, if the ISC valve begins to become clogged, the ISCvalve's response becomes worse so that the amounts of changes in the ISCopening degree and AFM measured air amount Ga are too small during thereference time. Thus, it is possible to predict the travel distanceremaining before the engine stalls due to a clogged ISC valve bymonitoring the amounts of changes in the ISC opening degree or AFMmeasured air amount Ga arising during the reference time.

In the third embodiment, which has been described above, the traveldistance remaining before the NG state is established is predicted atthe information center 12. However, the present invention is not limitedto the use of such a method. Alternatively, the vehicle 10 may predictthe travel distance and transmit only the predicted travel distance tothe information center 12.

Fourth Embodiment

A fourth embodiment of the present invention will now be described. Whena Level 3 fault is encountered, the first and second embodiments, whichhave been described earlier, perform a recovery procedure to minimizethe influence of the fault. If, for instance, the air conditioner isunduly loaded (see FIG. 7), the first and second embodiments perform arecovery procedure for increasing the correction increase amount for theintake air amount Ga at the time of air-conditioner operation orincreasing the ISC guard value. The above correction increase amount,ISC guard value, and other parameters that are to be changed for theexecution of a recovery procedure are hereinafter referred to as the“recovery parameters.”

When an encountered Level 3 fault is repaired, there is no need toperform a recovery procedure. In other words, the values of the recoveryparameters, which are changed for the execution of a recovery procedure,are improper after the vehicle is repaired. When the dealer 14 repairs afault for which a recovery procedure is performed, the fourth embodimentcauses the dealer 14 to reset the recovery parameters to their initialvalues.

More specifically, in the present embodiment, it is assumed that therecovery parameters are not reset to their initial values when a“battery clear” procedure is performed, and the recovery parameters arereset to their initial values when the dealer 14 gives a specialexternal input to the ECU 16. Further, in this embodiment, the ECU 16records a history of parts changes and other events related to faultrepairs.

When a fault is repaired after the execution of a recovery procedure,the system according to the present embodiment allows the dealer 14 toproperly reset the recovery parameters to their initial values asdescribed above. Consequently, the system according to the presentembodiment properly avoids a situation where proper control cannot beexercised after fault repairs due to improperly maintained recoveryparameter values.

Fifth Embodiment

A fifth embodiment of the present invention will now be described withreference to FIG. 12. The system according to the fifth embodiment isimplemented when the ECU 16 and computer units 22, 26, which areincluded in the configuration shown in FIG. 1, perform processing stepsthat are described later with reference to FIG. 12.

The characteristics of the parts used for the vehicle usually varywithin a tolerance range. As regards parts that need to be controlledwith high accuracy, the control operations for the parts should becorrected upon parts replacement in order to comply with thecharacteristics of newly installed parts. In the system according to thepresent embodiment, therefore, the vehicle 10, information center 12,and dealer 14 exchange necessary data so as to implement the requiredfunctionality.

FIG. 12 is a flowchart illustrating processing steps that the presentembodiment performs in order to implement the above functionality.According to the routine shown in FIG. 12, after replacing a vehiclepart (step 250), the dealer 14 transmits the specified number of areplacement part, the characteristic data of the part, and the specifiednumber of the affected vehicle to the information center 12. Thesetransmitted data are hereinafter referred to as the “replacement data.”

The term “characteristic data” refers to data that accurately representsthe input/output characteristics of a replacement part. If, forinstance, the ISC valve is replaced, the opening degree vs. flow ratecharacteristic measured of the ISC valve that is used as the replacementpart is transmitted to the information center 12 as the characteristicdata.

When receiving the replacement data from the dealer 14 (step 260), theinformation center 12 registers the data in the database (step 262).Next, the information center 12 reads the vehicle information relatingto the control of the replacement part from the database (step 264). Itis be noted that the vehicle information read out here is supplied fromthe vehicle 10 to the information center 12 via a communications link inadvance or is supplied as needed in compliance with a request from theinformation center 12 (step 270).

In accordance with the replacement data supplied from the dealer 14 andthe vehicle information supplied from the vehicle 10, the informationcenter 12 calculates a matching value for exercising accurate controlover the replacement part (step 266). When the matching value iscalculated, the information center 12 transmits the calculated matchingvalue to the vehicle 10 (step 268).

Upon receipt of the matching value from the information center 12, thevehicle 10 performs a setup process for ensuring that the matching valueis reflected in the control (steps 280 and 282). As described above, thesystem according to the present embodiment can set a matching value,which matches the characteristics of a replacement part, within thevehicle 10 when a part of the vehicle 10 is replaced. The systemaccording to the present embodiment, therefore, permits the vehicle 10to exercise replacement parts control with high accuracy immediatelyafter parts replacement.

In the fifth embodiment, which has been described above, the informationcenter 12 also uses the vehicle information when calculating thematching value. However, the present invention is not limited to the useof such a method. The matching value for a replacement part mayalternatively be calculated only on the basis of replacement datatransmitted from the dealer 14.

Sixth Embodiment

A sixth embodiment of the present invention will now be described withreference to FIG. 13. In the third embodiment, which has been describedearlier, the information center 12 detects a sign of a fault in thevehicle 10 in accordance with various information supplied from thevehicle 10, and predicts the possible travel distance remaining beforethe vehicle 10 becomes unable to run. If, for instance, a sign of aclogged ISC valve is detected, the information center 12 notes the signand predicts the possible travel distance remaining before the ISC valvefails to properly operate. When the possible travel distance iscalculated, the information center 12 supplies the calculated value tothe vehicle 10 and dealer 14 to provide against a vehicle fault.

FIG. 13 illustrates the relationship between the vehicle travel distanceand a sign of ISC valve clogging (AFM measured air amount Ga prevailingwhen the ISC opening remains unchanged). As indicated in FIG. 13, whenthe ISC valve is clogged, the AFM measured air amount Ga tends todecrease while the ISC opening degree remains unchanged. The systemaccording to the third embodiment monitors such a tendency to decreaseand predicts the travel distance remaining before the engine stalls dueto a clogged ISC valve.

FIG. 13 illustrates a case where the ISC valve is replaced with a newone before the former is completely clogged. As indicated in FIG. 13,the possible travel distance remaining before the vehicle 10 becomesunable to run should inevitably be reset (set to the maximum value) whena part that is the cause of the fault (ISC valve in this case) isreplaced. The system according to the present embodiment, therefore,resets all data concerning the possible travel distance when the partthat has been the cause of the calculation of the possible traveldistance is replaced in the dealer 14.

More specifically, the information about the possible travel distance,which is possessed by the vehicle 10, information center 12, and dealer14, is reset upon parts replacement. More concretely, the possibletravel distance information possessed by the vehicle 10 is not reset bya “battery clear” whereas being resets when a special external input isgiven to the ECU 16 at the dealer 14. The information possessed by theinformation center 12 is reset upon receipt of a communication from thedealer.

According to the above procedure, it is possible to properly reset theinformation about the possible travel distance that is set stemming froma deteriorated part when the part that has been the cause of thecalculation of a possible travel distance is repaired, in the presentembodiment. As a result, the system according to the present embodimentproperly prevents the possible travel distance information that is setbefore parts replacement from being unreasonably retained after partsreplacement.

The features and effect of the present invention can be summarized asfollows.

The first aspect of the present invention accords with a vehicle faultdiagnostic system, which includes a vehicle and an information centerthat are capable of communicating with each other, the vehicle faultdiagnostic system comprising: vehicle data detection means that isinstalled in the vehicle to detect vehicle data; fault detection meansthat is installed in the vehicle or in the information center to detecta vehicle fault in accordance with said vehicle data; identificationprocess instruction means that is installed in the information center tofind arising of the vehicle fault and to instruct the vehicle to performa fault identification process for identifying the cause of the vehiclefault; identification process execution means that is installed in thevehicle to perform the fault identification process that is instructed;identification process result return means that is installed in thevehicle to return the result of said fault identification process to theinformation center; fault location identification means that isinstalled in the information center to identify the fault location inaccordance with the result of said fault identification process, whichis returned from the vehicle; and identified fault countermeasure meansthat is installed in the information center to take countermeasuresagainst the identified fault.

The second aspect of the present invention accords with the vehiclefault diagnostic system according to the first aspect of the presentinvention, wherein said identified fault countermeasure means includesrecovery process instruction means for instructing the vehicle toperform a recovery process for eliminating the influence of theidentified fault, the vehicle fault diagnostic system furthercomprising: recovery process execution means that is installed in thevehicle to perform the recovery process that is instructed; and processdetermination means that is installed in the vehicle or in theinformation center to determine in accordance with the result of saidrecovery process whether another recovery process should be continued ornot.

The third aspect of the present invention accords with the vehicle faultdiagnostic system according to the second aspect of the presentinvention, wherein said recovery process instruction means includes mostserious fault storage means for storing most serious faults and recoverytarget limiting means for issuing instructions for performing saidrecovery process only when a detected fault is one of the most seriousfaults.

The fourth aspect of the present invention accords with the vehiclefault diagnostic system according to any one of the first to thirdaspects of the present invention, wherein said identification processinstruction means includes serious fault storage means for storingserious faults and identification target limiting means for issuinginstructions for performing said fault identification process only whena detected fault is serious.

The fifth aspect of the present invention accords with a vehicle faultdiagnostic system, which includes a vehicle and an information centerthat are capable of communicating with each other, the vehicle faultdiagnostic system comprising: vehicle data detection means that isinstalled in the vehicle to detect vehicle data; fault detection meansthat is installed in the vehicle or in the information center to detecta vehicle fault in accordance with said vehicle data; recovery processinstruction means that is installed in the information center to findarising of the vehicle fault and to instruct the vehicle to perform arecovery process for eliminating the influence of the vehicle fault;recovery process execution means that is installed in the vehicle toperform the recovery process that is instructed; and processdetermination means that is installed in the vehicle or in theinformation center to determine in accordance with the result of saidrecovery process whether another recovery process should be continued ornot.

The sixth aspect of the present invention accords with the vehiclefault, diagnostic system according to the fifth aspect of the presentinvention, wherein said recovery process instruction means includes mostserious fault storage means for storing most serious faults and recoverytarget limiting means for issuing instructions for performing saidrecovery process only when a detected fault is one of the most seriousfaults.

The seventh aspect of the present invention accords with a vehicle faultdiagnostic system, which includes a vehicle and an information centerthat are capable of communicating with each other, the vehicle faultdiagnostic system comprising: fault characteristic value detection meansthat is installed in the vehicle to detect a fault characteristic valuestemming from arising of a particular fault; fault seriousnessdetermining means for determining the serious degree of detected saidfault in accordance with the magnitude of said fault characteristicvalue; and supply information limiting means for supplying the detectedinformation about said fault to the information center only when saidserious degree exceeds a judgment value.

The eighth aspect of the present invention accords with the vehiclefault diagnostic system according to the seventh aspect of the presentinvention, the system further comprising: recovery process instructionmeans that is installed in the information center to instruct thevehicle to perform a recovery process for eliminating the influence ofsaid fault whose information is supplied from the vehicle; recoveryprocess execution means that is installed in the vehicle to perform therecovery process that is instructed; and process determination meansthat is installed in the vehicle or in the information center todetermine in accordance with the result of said recovery process whetheranother recovery process should be continued or not.

The ninth aspect of the present invention accords with the vehicle faultdiagnostic system according to the eighth aspect of the presentinvention, wherein said supply information limiting means suppliesinformation including said fault characteristic value to the informationcenter as the information about said fault, and wherein said recoveryprocess instruction means includes urgency judgment means, which, whenthe information about said fault is supplied from the vehicle, judges inaccordance with said fault characteristic value whether the fault shouldbe recognized as an urgent fault; and recovery target limiting means forissuing instructions for performing said recovery process only when saidfault whose information is supplied from the vehicle is urgent.

The tenth aspect of the present invention accords with the vehicle faultdiagnostic system according to any one of the seventh to ninth aspectsof the present invention, the system further comprising: identificationprocess instruction means that is installed in the information center toinstruct the vehicle to perform a fault identification process foridentifying the cause of said fault whose information is supplied fromthe vehicle; identification process execution means that is installed inthe vehicle to perform the fault identification process that isinstructed; identification process result return means that is installedin the vehicle to return the result of said fault identification processto the information center; and fault location identification means thatis installed in the information center to identify a fault location inaccordance with the result of said fault identification process, whichis returned from the vehicle.

The eleventh aspect of the present invention accords with the vehiclefault diagnostic system according to any one of the first to tenthaspects of the present invention, wherein said fault identificationprocess includes a plurality of inspection modes, and wherein said faultlocation identification means includes identification process completionmeans, which determines that the fault identification process iscompleted when a fault location can be identified in accordance with afault identification process result that is returned from the vehicle;and identification process continuation means, which causes saididentification process instruction means to instruct the start of aninspection mode corresponding to the result when the fault locationcannot be identified in accordance with said result.

The twelfth aspect of the present invention accords with the vehiclefault diagnostic system according to any one of the first to eleventhaspects of the present invention, the system further comprising: faultdistance estimation means that is installed in the vehicle or in theinformation center to estimate the travel distance remaining before afault occurs in the vehicle in accordance with said vehicle data; andeither fault distance display means for displaying said travel distanceremaining before a fault occurrence within the display or fault distancetransmission means for transmitting said travel distance to a vehiclemaintenance factory.

According to the first aspect of the present invention, the vehicle canreceive the instructions for a fault identification process from theinformation center when identifying the cause of the fault that isdetected in the vehicle. According to the present invention, therefore,the vehicle does not have to store the fault identification processingsteps to be performed for individual faults. As a result, theinformation processing load on the vehicle can be reduced.

According to the second aspect of the present invention, afteridentifying the fault that is cause of a defect, the vehicle can performa recovery process on board for eliminating the influence of the fault.In this instance, the vehicle can receive the instructions for therecovery process to be performed from the information center. Accordingto the present invention, therefore, the vehicle does not have to storethe recovery processing steps to be performed for individual faults. Asa result, the information processing load on the vehicle can be reduced.

According to the third aspect of the present invention, a recoveryprocess is performed only when one of the most serious faults isdetected. Therefore, the present invention can minimize the possibilityof processing load generation for recovery process execution.

According to the fourth aspect of the present invention, a faultidentification process is performed only when a serious fault isdetected. Therefore, the present invention can minimize the possibilityof processing load generation for fault identification processexecution.

According to the fifth aspect of the present invention, when detecting afault the vehicle can perform a recovery process on board foreliminating the influence of the fault. In this instance, the vehiclecan receive the instructions for the recovery process to be performedfrom the information center. According to the present invention,therefore, the vehicle does not have to store the recovery processingsteps to be performed for individual faults. As a result, theinformation processing load on the vehicle can be reduced.

According to the sixth aspect of the present invention a recoveryprocess is performed only when one of the most serious faults isdetected. Therefore, the present invention can minimize the possibilityof processing load generation for recovery process execution.

According to the seventh aspect of the present invention, it is possibleto judge whether a fault that is detected on the vehicle is urgent ornot on the basis of a fault characteristic value. When the urgency ofthe fault is low, it is possible to skip a process for supplying theinformation about the fault to the information center, even if the faultis one that requires immediate countermeasure when having a highurgency. As a result, the present invention can avoid unnecessarycommunication to effectively reduce the processing load on the vehicle.

According to the eighth aspect of the present invention, when aparticular fault having a great fault characteristic value occurs in thevehicle, the vehicle is permitted to perform a recovery process foreliminating the influence of the fault. In this instance, the vehiclecan receive the instructions for the recovery process to be performedfrom the information center. According to the present invention,therefore, the vehicle does not have to store the recovery processingsteps to be performed for individual faults. As a result, theinformation processing load on the vehicle can be reduced.

According to the ninth aspect of the present invention, in a case wherea fault information is supplied from the vehicle to the informationcenter, a recovery process is performed only when the fault is urgent.Therefore, the present invention can minimize the possibility ofprocessing load generation for recovery process execution.

According to the tenth aspect of the present invention, the cause of afault is identified when the fault is detected in the vehicle having agreat fault characteristic value. In this instance, the vehicle canreceive the instructions for a fault identification process from theinformation center. According to the present invention, therefore, thevehicle does not have to store the fault identification processing stepsto be performed for individual faults. As a result, the informationprocessing load on the vehicle can be reduced.

According to the eleventh aspect of the present invention, the vehiclecan perform a fault identification process that includes a plurality ofinspection modes. Therefore, the present invention can properly identifya fault whose identification requires the execution of a complicatedprocess.

According to the twelfth aspect of the present invention, it is possibleto estimate the travel distance remaining before an expected faultoccurrence in the vehicle, and display the estimated value within thevehicle or transmit it to a maintenance factory. Therefore, the presentinvention makes it possible to take appropriate early measures beforethe occurrence of a fault.

In the first embodiment, which has been described earlier, the “vehicledata detection means” according to the first aspect of the presentinvention is implemented when the vehicle 10 performs processing step100; the “fault detection means” according to the first aspect of thepresent invention is implemented when the information center 12 performsprocessing step 114; the “identification process instruction means” and“fault location identification means” according to the first aspect ofthe present invention are implemented when the information center 12performs processing step 118; the “identification process executionmeans” according to the first aspect of the present invention isimplemented when the vehicle 10 performs processing step 122; the“identification process result return means” according to the firstaspect of the present invention is implemented when the vehicle 10performs processing step 124; and the “identified fault countermeasuremeans” according to the first aspect of the present invention isimplemented when the information center 12 performs processing steps 130to 136.

In the first embodiment, which has been described earlier, the “recoveryprocess instruction means” and “process determination means” accordingto the second aspect of the present invention are implemented when theinformation center 12 performs processing steps 134 and 136; and the“recovery process execution means” according to the second aspect of thepresent invention is implemented when the vehicle 10 performs processingstep 152.

In the first embodiment, which has been described earlier, the “mostserious fault storage means” and “recovery target limiting means”according to the third aspect of the present invention are implementedwhen the information center 12 performs processing step 134.

In the first embodiment, which has been described earlier, the “seriousfault storage means” and “identification target limiting means”according to the fourth aspect of the present invention are implementedwhen the information center 12 performs processing step 116.

In the first embodiment, which has been described earlier, the “vehicledata detection means” according to the fifth aspect of the presentinvention is implemented when the vehicle 10 performs processing step100; the “fault detection means” according to the fifth aspect of thepresent invention is implemented when the information center 12 performsprocessing step 114; the “recovery process instruction means” and“process determination means” according to the fifth aspect of thepresent invention are implemented when the information center 12performs processing steps 134 and 136; and the “recovery processexecution means” according to the fifth aspect of the present inventionis implemented when the vehicle 10 performs processing step 152.

In the first embodiment, which has been described earlier, the “mostserious matter storage means” and “recovery target limiting means”according to the sixth aspect of the present invention are implementedwhen the information center 12 performs processing step 134.

In the first embodiment, which has been described earlier, the“identification process completion means” according to the eleventhaspect of the present invention is implemented when the informationcenter 12 performs processing step 162, 166, 170, 174, or 176 asindicated in FIG. 4; and the “identification process continuation means”according to the eleventh aspect of the present invention is implementedwhen it is judged in steps 160, 164, 168, and 172 that the condition isnot established.

In the second embodiment, which has been described earlier, the enginespeed Ne prevailing in the event of an undue decrease in the enginespeed, the acceleration and vehicle speed change prevailing in the eventof an acceleration failure, the microphone output generated in the eventof abnormal sound generation, the knock intensity prevailing in theevent of an abnormal knock, and the like correspond to the “faultcharacteristic value”; the “fault characteristic value detection means”according to the seventh aspect of the present invention is implementedwhen the ECU 16 detects a fault characteristic value in step 100; andthe “fault seriousness determining means” and “supply informationlimiting means” according to the seventh aspect of the present inventionare implemented when the ECU 16 performs processing step 102.

In the second embodiment, which has been described earlier, the“recovery process instruction means” and “process determination means”according to the eighth aspect of the present invention are implementedwhen the information center 12 performs processing steps 134 and 136;and the “recovery process execution means” according to the eighthaspect of the present invention is implemented when the vehicle 10performs processing step 152.

In the second embodiment, which has been described earlier, the “urgencyjudgment means” and “recovery target limiting means” according to theninth aspect of the present invention are implemented when theinformation center 12 performs processing step 134.

In the second embodiment, which has been described earlier, the“identification process instruction means” and “fault locationidentification means” according to the tenth aspect of the presentinvention are implemented when the information center 12 performsprocessing step 118; the “identification process execution means”according to the tenth aspect of the present invention is implementedwhen the vehicle 10 performs processing step 122; and the“identification process result return means” according to the tenthaspect of the present invention is implemented when the vehicle 10performs processing step 124.

In the third embodiment, which has been described earlier, the “faultdistance estimation means” according to the twelfth aspect of thepresent invention is implemented when the information center 12 performsprocessing step 218; the “fault distance display means” according to thetwelfth aspect of the present invention is implemented when the vehicle10 performs processing step 232; and the “fault distance transmissionmeans” according to the twelfth aspect of the present invention isimplemented when the information center 12 performs processing step 220.

1. A vehicle fault diagnostic system, which includes a vehicle and an information center that are capable of communicating with each other, the vehicle fault diagnostic system comprising: vehicle data detection means that is installed in the vehicle to detect vehicle data; fault detection means that is installed in the vehicle or in the information center to detect a vehicle fault in accordance with said vehicle data; identification process instruction means that is installed in the information center to find arising of the vehicle fault and to instruct the vehicle to perform a fault identification process for identifying the cause of the vehicle fault; identification process execution means that is installed in the vehicle to perform the fault identification process that is instructed; identification process result return means that is installed in the vehicle to return the result of said fault identification process to the information center;. fault location identification means that is installed in the information center to identify the fault location in accordance with the result of said fault identification process, which is returned from the vehicle; and identified fault countermeasure means that is installed in the information center to take countermeasures against the identified fault, wherein said identified fault countermeasure means includes recovery process instruction means for instructing the vehicle to perform a recovery process for eliminating the influence of the identified fault, the vehicle fault diagnostic system further comprising: recovery process execution means that is installed in the vehicle to make the vehicle itself perform the recovery process that is instructed; and process determination means that is installed in the vehicle or in the information center to determine in accordance with the result of said recovery process whether another recovery process should be continued or not.
 2. The vehicle fault diagnostic system according to claim 1, wherein said recovery process instruction means includes most serious fault storage means for storing most serious faults and recovery target limiting means for issuing instructions for performing said recovery process only when a detected fault is one of the most serious faults.
 3. The vehicle fault diagnostic system according to claim 1, wherein said identification process instruction means includes serious fault storage means for storing serious faults and identification target limiting means for issuing instructions for performing said fault identification process only when a detected fault is serious.
 4. The vehicle fault diagnostic system according to claim 1, wherein said fault identification process includes a plurality of inspection modes, and wherein said fault location identification means includes identification process completion means, which determines that the fault identification process is completed when a fault location can be identified in accordance with a fault identification process result that is returned from the vehicle; and identification process continuation means, which causes said identification process instruction means to instruct the start of an inspection mode corresponding to the result when the fault location cannot be identified in accordance with said result.
 5. The vehicle fault diagnostic system according to claim 1, further comprising: fault distance estimation means that is installed in the vehicle or in the information center to estimate the travel distance remaining before a fault occurs in the vehicle in accordance with said vehicle data; and either fault distance display means for displaying said travel distance remaining before a fault occurrence within the display or fault distance transmission means for transmitting said travel distance to a vehicle maintenance factory.
 6. A vehicle fault diagnostic system, which includes a vehicle and an information center that are capable of communicating with each other, the vehicle fault diagnostic system comprising: vehicle data detection means that is installed in the vehicle to detect vehicle data; fault detection means that is installed in the vehicle or in the information center to detect a vehicle fault in accordance with said vehicle data; recovery process instruction means that is installed in the information center to find arising of the vehicle fault and to instruct the vehicle to perform a recovery process for eliminating the influence of the vehicle fault; recovery process execution means that is installed in the vehicle to make the vehicle itself perform the recovery process that is instructed; and process determination means that is installed in the vehicle or in the information center to determine in accordance with the result of said recovery process whether another recovery process should be continued or not.
 7. The vehicle fault diagnostic system according to claim 6, wherein said recovery process instruction means includes most serious fault storage means for storing most serious faults and recovery target limiting means for issuing instructions for performing said recovery process only when a detected fault is one of the most serious faults.
 8. A vehicle fault diagnostic system, which includes a vehicle and an information center that are capable of communicating with each other, the vehicle fault diagnostic system comprising: fault characteristic value detection means that is installed in the vehicle to detect a fault characteristic value stemming from arising of a particular fault; fault seriousness determining means for determining the serious degree of detected said fault in accordance with the magnitude of said fault characteristic value; and supply information limiting means for supplying the detected information about said fault to the information center only when said serious degree exceeds a judgment value; recovery process instruction means that is installed in the information center to instruct the vehicle to perform a recovery process for eliminating the influence of said fault whose information is supplied to the vehicle; recovery process execution means that is installed in the vehicle to make the vehicle itself perform the recovery process that is instructed; and process determination means that is installed in the vehicle or in the information center to determine in accordance with the result of said recovery process whether another recovery process should be continued or not.
 9. The vehicle fault diagnostic system according to claim 8, wherein said supply information limiting means supplies information including said fault characteristic value to the information center as the information about said fault, and wherein said recovery process instruction means includes urgency judgment means, which, when the information about said fault is supplied from the vehicle, judges in accordance with said fault characteristic value whether the fault should be recognized as an urgent fault; and recovery target limiting means for issuing instructions for performing said recovery process only when said fault whose information is supplied from the vehicle is urgent.
 10. The vehicle fault diagnostic system according to claim 7 or 9, further comprising: identification process instruction means that is installed in the information center to instruct the vehicle to perform a fault identification process for identifying the cause of said fault whose information is supplied from the vehicle; identification process execution means that is installed in the vehicle to perform the fault identification process that is instructed; identification process result return means that is installed in the vehicle to return the result of said fault identification process to the information center; and fault location identification means that is installed in the information center to identify a fault location in accordance with the result of said fault identification process, which is returned from the vehicle. 